Mental Exhaustion Before Exercise May Hinder Your Workout

We all have tight schedules, but a recent study found that if you do something mentally draining before exercising, your workout may be less effective — even if your muscles are well rested.

Photo by John Millar

The study, performed at the University of Kent in England and the French Institute of Health and Medical Research, aimed to uncover how mental exhaustion affects physical exercise. After performing either a mentally draining or mentally relaxing task, participants performed a series of leg exercises, hooked up to a set of electrodes designed to measure muscle fatigue. They were also asked to report how tired they felt during the workout.

The New York Times explains the results:

As it turned out, mental fatigue significantly affected the men’s endurance. They tired about 13 per cent faster after the computer test than after watching “Earth.” They also reported that the workout felt far more taxing.

But, interestingly, their maximum contractile force was about the same after each session. Their muscles responded just as robustly to orders from the brain and the attached electrode after the draining mental workout as after the quiet session, even though the brain-fogged volunteers felt as if their muscles were much more exhausted. . .

. . .In simpler terms, exercise simply feels harder when your brain is tired, so you quit earlier, although objectively, your muscles are still somewhat fresh.

It’s the first study to explore the subject, but it’s an interesting result that deserves a closer look. Check out the link below to read the full study, or check out the New York Times’ article about it here.

Prolonged Mental Exertion Does Not Alter Neuromuscular Function of the Knee Extensors [Medicine & Science in Sports & Exercise via New York Times]